A semiconductor apparatus may operate by being supplied with an external voltage from an exterior. The semiconductor apparatus may start to operate when the external voltage rises over an appropriate level in an initializing operation. Accordingly, the semiconductor apparatus may include a power-up circuit to detect the level of the external voltage.
The power-up circuit of the semiconductor apparatus may detect the level of the external voltage and activate a power-up signal when the external voltage rises over the appropriate level. The semiconductor apparatus may start an internal operation only when the power-up signal is activated.